Abstract—Gear transmission error (TE) is the predominant source of dynamic excitation and via a complex transfer function produces noise in the powertrain system. Minimizing transmission error is crucial for reducing gear noise. In this paper, an external helical gear pair is modeled and analyzed by an experimentally validated 3D-TCA method ̶ GATES considering manufacturing deviation. By comparing the simulation results, the profile and lead tooth micro-modifications are compared to obtain a good result in gear transmission error and contact stress. Therefore, it is a good example to show on how to get the optimal gear tooth micro-geometry for minimum transmission error.